Sprockef-wheel



(No Model.)

P. FORG. SPROGKET WHEEL.

No. 550,749. Patented Dec. 3, 1895.

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PETER FORG, OF SOMERVILLE, MASSACHUSETTS.

SPRQCKET-WHEEL.

SPECIFICATION forming part of Letters Patent No. 550,749, dated December3, 1895.

Application filed May 8, 1895. Serial No. 548,486. (No model.)

To aZZ whom, it may concern:

Beit known that I, PETER FORG, residing in Somerville, in the county ofMiddleseX and State of Massachusetts, have invented an Improvement inSprocket-Wheels, of which the following description, in connection withthe accompanying drawings, is a specification, like letters and numeralson the drawings representing like parts.

This invention relates to a chain or sprocket wheel especially designedand adapted for use on bicycles and like vehicles.

The sprocket-wheel herein shown as embodying this invention is composedof a rim portion detachable from the center or body of the wheel; andone feature of this invention consists in an improved interlocking ofthese parts whereby they may be more securely and effectually securedtogether.

. Another feature of this invention consists in providing the teeth of asprocket-wheel with superior wearing surfaces, which are preferablyintegral with each other and formed from a single piece of metal, aswill be described.

These and other features of this invention will be pointed out in theclaims at the end of this specification.

Figure 1 is an elevation of one side of a sprocketwheel embodying thisinvention; Fig. 2, an elevation of the opposite side of the wheel shownin Fig. 1; Fig. 3, a sectional de tail, on an enlarged scale, of thewheel shown in Figs. 1 and 2, the section being taken on the line 3 3,Fig. 2 and Fig. 4, a detail, on an enlarged scale, to be referred to.

The sprocket-wheel herein represented as embodying myinvention may andpreferably will have its center or body portion A detachably secured tothe rim A 5 but the improvement in the construction of the rim, whichwill be hereinafter specifically pointed out, maybe embodied insprocket-wheels in which the center or body is not detachable from therim portion.

In bicycles as now commonly constructed it is especially desirous toreduce the weight of the various parts to a minimum without sacrificingstrength, and in order that this result may be accomplished withrelation to the sprocket-wheel I prefer to make the said sprocket wheelafter the manner herein shown. In accordance with this invention,therefore, the center or body portion A and the main portion of the rimA are struck or died out of sheet metal, preferably soft or mild steel,while the wearing portion of the said rim and teeth are also struck ordied out of a harder or superior grade of steel, preferably tool-steel.

The body or center A is preferably composed of a hub a and spokes orarms A,which for the best results are offset for the greater portion oftheir length with relation to a ver tical plane extended through thecenter of the rim and the hub. The main portion of the rim consists of asubstantially narrow ring a preferably of soft steel, having a series ofinwardly-projecting arms a corresponding in number to the spokes or armsa, and either the spokes a are made wider than the arms a or vice versa,so that the wider part may be provided with a slot or recess into whicha flange, finger, or interlocking projection on the other part may fitsomewhat snugly to join or connect together the saidparts.

In the present instance the arms a of the ring a are made wider than thespokes a, and the arms a are each provided with a slot a into whichprojects a bent finger or flange a on the spoke a, which in theconstruction herein. shown constitutes the interlocking projection, thesaid finger or flange fitting the slot a somewhat snugly, so as to lockthe rim and center of the wheel together.

The spokes a and arm a maybe firmly, but detachably, secured together byscrews or threaded rods or bolts a inserted through a suitable openingin the arms a and into and preferably through a threaded hole or openingin the spoke a, and,if desired,the threaded end of the screw or bolt aprojecting beyond the spoke a, may beprovided with a nut a asrepresented in Figs. 2 and 3; but this nut is not absolutely essentialand may be dispensed with. In this case the end of the screw-rod or bolta may be flush with the outside of the spoke a.

The screw-rods or bolts firmly fasten together the two parts of thesprocket-wheel; but this construction, broadly speaking, I'do not claim,as sprocket-wheels of this construction have heretofore been made; butthis construction of sprocket-wheel is objectionable,

as in practice a very considerable strain comes upon the screw-rods orbolts, which soon work loose, thereby destroying the effectiveness ofthe wheel.

By my improved construction it will be seen that the strain comes uponthe interlocking parts, which are fitted snugly together, and the twoparts of the wheel are locked against movement with relation to eachother, and consequently the screw-rods or bolts are relieved from strainand do not work loose, so that the sprocket-wheel made in two parts, asherein shown, is as strong as if the spokes and rim were integral. Thisfeature of my invention may be embodied in a sprocketwheel in which therim may be of any desired or suitable construction; but Iprefer to makethe rim after the manner herein shown.

In accordance with this second feature of this invention the ring a isprovided at suitable intervals about its periphery with teeth I), whichare preferably integral with the said ring, the said teeth, ring, andarms a being preferably made of soft or mild steel to obtain the desiredstrength, and the said parts are preferably cut out of sheet stock inone piece.

When the teeth I) are made of soft or mild steel,they are preferablyreinforced with j ackets 17 preferably of harder metal, such astool-steel, which jackets constitute the wearing-surface for the teethand take the wear of the link-chain commonly employed on bicycles.

The jackets b for the teeth I) of the rim may be made integral orseparate but I prefer to make them integral with each other, whichresult may, and preferably will, be accomplished as will now bedescribed.

A flat strip of sheet metal, preferably tool or hardened steel, of thedesired width, is cut out by a suitable die, (not shown,) so, as toleave openings Zr, separated by cross-pieces or end walls 71 and boundedby side walls 19 b after the manner shown in Fig. 4. The opening b ispreferably made hexagonal in shape, and

tum-shaped parts 10 12, the bases of which parts are joined with theside walls or bars b 11 and the narrower portions of which parts areunited substantially on a central line, so that the strip thus formedmay be bent longitudinally on a central line, which bending may beeffected by acting upon the flat strip with, suitably-shaped dies orrolls, which give.

mating the form of the sprocket-wheel rim.

By the operations just described the parts 10. 12 are shaped to fit overand embrace the teeth I) of the rim, while the side walls 19 b embracethe opposite sides of the ring a and the inner edges 14 15 of the sidewallsb 19 of each opening are substantially flush with the outercircumference of the ring a? and constitute wearing-surfaces. for thatportion of the ring a between the teeth b.

WVhen the reinforcing-strip shown in Fig. 4

is shaped as described and applied to the ring a after the mannerrepresented in Figs. 1, 2, and 3, the ends of the reinforcing-strip maybe brazed together, or the strip may be fastened on opposite sides ofthe point of contact of the two ends of the reinforcing-strip by meansof rivets or pins 0 c,inserted through the reinforcing-strip and thering a or in any other suitable manner. This construction of the rimportion of the sprocket-wheel permits the ring a to be made ofsubstantially thin metal and of a soft steel to obtain increasedstrength, while at the same time the wearingsurface of thesprocket-wheel is of the desired hardness. This reinforcing feature ofmy invention when coupled with the interlocking feature of the inventionproduces a sprocket-wheel which is light, yet strong and cheap tomanufacture. I, however, do not desire to limit the reinforcing featureof this invention to a sprocket-wheel made in two parts and interlocked,as described, as the reinforcin g feature may be applied to asprocketwheel in which the rim and center or body are in one piece, andin this case the center or body and rim may be made of a soft steel toobtain increased strength, and the desired hardness maybe obtained bythe reinforcing band or wearing-surface.

I prefer that the reinforcing wearing-surface should be made afterthemanner above describedthat is, with the jackets for the I teeth I)connected by the side walls 19 12 but I do not desire to limit myinvention to a reinforcin g wearing-surface in which the jackets for theteeth are connected together, as

each jacket may be separated from its adjacent jacket and riveted orotherwise suitably secured to the rim of the sprocket-wheel. Byreference to Figs. 1, 2, and 3 it will be seen that, the spokes are madeby offsetting I or dishing out a piece from which the spokes are formed,which offset construction gives increased strength to the sprocket-wheeland permits the center of the wheel to be made very light and of aminimum amount of metal. the end walls 17 are each composed of frus- I 1ing for the shaft, thehub a'is pressed or drawn 1 out to elongate thesame.

In order to obtain a substantiallylong bear- Believing myself to. be thefirst to construct a sprocket-wheel with interlocking rim and 1 spokes,whereby the fastening screws or devices are relieved from strain, Idonot desire to limit my invention to. the particular constructionshown. to the bent strip an annular form approXi- I claim- 1. In asprocket wheel, the combination of 1 the following instrumentalities,viz :-a metal j rim provided with teeth, a center or body portiondetachably secured to the rim and interlocked therewith by theengagement of one,

part with a slot or recess in the other part, and devices extendedthrough the said interlocked parts to firmly but detachablysecure saidparts and which devices are relieved from strain by the interlocking ofthe said parts, substantially as described.

2. In a sprocket wheel, the combination of the followinginstrumentalities, viz :a metal rim provided with teeth integraltherewith and composed of a substantially soft metal, a metal body orcenter interlocked with said rim, devices extended through the saidinterlocking parts to firmly but detachably secure the said partstogether and which devices are relieved from strain by the interlockingof said parts, and metal jackets for the said teeth composed of asuperior metal and embracing only the sides of the teeth and formtheside walls embracing the sides of the rim and forming the Wearingsurfaces thereof between the teeth, substantially as described.

4. In a sprocket-wheel, the combination of the followinginstrumentalities, viz :a metal rim provided with teeth, a center orbody portion attached to said rim, and a reinforcing connected jacketembracing both sides of the said teeth and the said rim, and consistingof a metal strip provided with openings separated by cross pieces andconnected side walls, and bent longitudinally on a substantially centralline, the said cross pieces embracing the sides of the teeth and thesaid side walls embracing the sides of the rim, the openings in thejacket leaving uncovered the front and rear ends of the teeth and theouter circumference of the rim between the teeth, substantially asdescribed.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

PETER FORG.

WVitnesses J AS. H. CHURCHILL, HERMAN FORG.

